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Fri, 11 Apr 2025 10:07:20 -0700 (PDT) Date: Fri, 11 Apr 2025 13:07:20 -0400 From: Johannes Weiner To: Brendan Jackman Cc: Andrew Morton , Vlastimil Babka , Mel Gorman , Carlos Song , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 2/2] mm: page_alloc: tighten up find_suitable_fallback() Message-ID: <20250411170720.GD366747@cmpxchg.org> References: <20250407180154.63348-1-hannes@cmpxchg.org> <20250407180154.63348-2-hannes@cmpxchg.org> <20250411134550.GB366747@cmpxchg.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: D13BF40014 X-Stat-Signature: pyseyfrwwzmiqjqripf6egs8q3wujk1u X-Rspam-User: X-HE-Tag: 1744391242-906240 X-HE-Meta: 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 KuvoLVd4 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Fri, Apr 11, 2025 at 03:07:01PM +0000, Brendan Jackman wrote: > On Fri Apr 11, 2025 at 1:45 PM UTC, Johannes Weiner wrote: > >> - if (find_suitable_fallback(area, order, migratetype, true) >= 0) > >> + if (should_try_claim_block(order, migratetype) && > >> + find_fallback_migratetype(area, order, migratetype) >= 0) > > > > So I agree with pushing the test into the callers. However, I think > > the name "should_try_claim_block()" is not great for this. It makes > > sense in the alloc/fallback path, but compaction here doesn't claim > > anything. It just wants to know if this order + migratetype is > > eligible under block claiming rules. > > > > IMO this would be more readable with the old terminology: > > > > if (can_claim_block(order, migratetype) && > > find_fallback_migratetype(area, order, migratetype) >= 0) > > Sure, that makes sense, here's a modified version of the patch: > > --- > > From 85be0fca4627c5b832a3382c92b6310609e14ca4 Mon Sep 17 00:00:00 2001 > From: Brendan Jackman > Date: Thu, 10 Apr 2025 13:22:58 +0000 > Subject: [PATCH] mm: page_alloc: Split up find_suitable_fallback() > > Now that it's been simplified, it's clear that the bool arg isn't > needed, callers can just use should_try_claim_block(). Once that logic > is stripped out, the function becomes very obvious and can get a more > straightforward name and comment. > > Since should_try_claim_block() is now exported to compaction.c, give it > a name that makes more sense outside the context of allocation - > should_claim_block() seems confusing in code that has no interest in > actually claiming a block. > > Signed-off-by: Brendan Jackman Acked-by: Johannes Weiner Thanks! One minor nit: > @@ -914,8 +914,9 @@ static inline void init_cma_pageblock(struct page *page) > #endif > > > -int find_suitable_fallback(struct free_area *area, unsigned int order, > - int migratetype, bool claimable); > +int find_fallback_migratetype(struct free_area *area, unsigned int order, > + int migratetype); > +bool can_claim_block(unsigned int order, int start_mt); Switch those around to match the C file order? (Just being extra, and this is probably a losing battle, but hey...)